This invention relates to a street sweeper machine for trash collecting.
Known type street sweepers intended for cleaning large surfaces, such as streets, generally have a driver's cab, a storage tank for the water to be sprinkled over the ground to wet it prior to removing trash and to prevent dust raising, a container for trash picked up from the ground, and a number of brushes in direct contact with the ground.
Necessary in each machine of the aforesaid type, which are expected to operate continuously for many hours every day, are in particular a container for trash and a large capacity tank, in order to provide adequate range and avoid frequent stops for unloading trash and refilling with water. Also appropriate is a driver's cab to prevent him from becoming excessively tired.
It is also generally arranged for the brushes to include on each machine both side brushes of cup-like shape and a cylindrical brush or roller, located substantially centrally on the machine and forming the main element at work over the ground.
The cup-like brushes include, in turn, at least two adjustable level side brushes substantially within the machine outline and serving the purpose of directing removed material or trash to underneath the machine and towards the main center roller.
The center roller is also usually adjustable in level and serves to both sweep the ground and thrust all the trash, including that from the side brushes, toward the interior of the trash container.
In many cases the container accommodates an auxiliary roller on its interior which is driven off the main roller through a belt drive and is arranged to favor the trash movement into the container by boosting the thrusting action of the main roller and prevent trash from moving out especially where large size trash is involved.
Both at said brushes and, especially, at the main center roller, water sprinkling nozzles are provided which are connected to the cited water storage tank and a pump. The water sprinkled toward the ground traps down the dust raised by the cup-like brushes and the roller.
In particular an array of sprinklers and a strong sprinkling action at the very location of the main center roller are provided, since the same performs a trash raising and thrusting action toward the container which typically raises dust. Dust propagates to the area of the main center roller also from the inlet to the trash container.
Some street sweepers include an additional or auxiliary brush, in addition to the two side brushes, which is arranged laterally and forwardly of the frame and serves to pick up trash from either the street sides or the sidewalks. This additional brush directs trash toward the two side brushes and moves out of the machine outline to readily reach also difficult-to-clean spots with just the two side brushes which equip the machine.
A first drawback of the machines just described is that they are too bulky, on account of said requirements for a large size trash container, large capacity water storage tank, comfortable driver's cab, and of the trash-directing devices. Bulk is objectionable because it interferes with fast manoeuvers to reach all spots to be cleaned and negotiate any obstacles. The bulk of such machines also causes problems with normal street traffic.
Another drawback of known type sweepers is that the main center roller, albeit assisted in its function of thrusting trash into the container by a suitable device, tends to build up trash within the container in a close-by area. Thus, trash is not deposited evenly over the container bottom, failing to utilize the full capacity thereof, and the trash build-up tends to hinder the entrance of more trash.
It should be further noted that in spite of the water sprinkling arrangement the rotating brushes and roller raise dust in large amounts, which dust is diffused through the air and cannot be directed into the container and is later deposited back over the ground. Furthermore, in cold climates or during the winter season, the use of water to attenuate dust raising creates the so-called "varnish effect", that is, formation of thin ice layers.
Not the least of its drawbacks is that said additional brush is only adapted to operate on one side of the machine, thus requiring inconvenient and difficult manoeuvering by the operator to get, for example, at trash on the opposite side of the street with respect to the sweeper travel direction.